Signs for display in car windows are well known. In all cases the sign is deployed inside the vehicle with the message of the sign oriented to be viewed by persons outside the vehicle.
The prior art includes signs intended for longer term advertising, such as the "Eat at Joe's" sign disclosed in U.S. Pat. No. 4,258,492 to Williams. This embodiment includes a frame to be mounted inside the window frame as may be convenient.
Another relatively permanent display is shown in U.S. Pat. No. 5,016,145 to Singleton in which an illuminated signboard, with a festive natal message is displayed through the rear window of a pick-up truck. The structure is mounted to the inside face of the rear window by means of suction cups.
A third form of relatively permanent structure is shown in U.S. Pat No. 5,069,376 to Barel. In this instance a formed sign holder is positioned between the rearwardly sloping inner face of a front windshield and the upper surface of the front dashboard. The holder permits insertion of, for example, a handicapped person or wheelchair sign, or a camping facility permit. Although the sign holder itself is stationary once installed the permit or sign may be removed and replaced as desired.
More interesting devices are shown in U.S. Pat. No. 4,864,754 to Sangu and U.S. Pat. No. 5,010,670 to Minervini. Both of these documents reveal signs which move from a stored position to a display position as the result of operation of a mechanism. The Sangu device includes not only an embodiment with a sophisticated microprocessor controlled system linked to the brake pedal and speedometer, but also a further embodiment comprising a geared prismatic array upon whose sides three messages may be arranged, in the manner of the well known revolving roadside billboards. For all its complexity the main Sangu embodiment is not a sign that is controlled by the driver to send display arbitrary messages to other drivers, but is, by contrast a display ancillary to the function of braking. The driver does not activate the sign itself, but rather the sign is incidentally, and indirectly activated by the action of stopping the car. The display may be installed on the rear decking behind the rear seat of a passenger sedan, or suspended from the roof. The Sangu device is clearly intended to be a permanent fixture within the vehicle.
Minervini discloses a movable sign of less permanence than Sangu, intended to be held in place by clips introduced between the inner lip of a window seal and the glass panel. Frequent removal and re-insertion of these clips would not improve the service life of the window seal, and might well lead to scratches of the interior panels of the vehicle. A lanyard extends from the distal extremity of an hinged, depending panel forward to a position within the reach of the conductor. This lanyard, and its operation, demonstrate certain disadvantages. First, the driver must reach up, while the car is in motion, and release the hook by which the lanyard is caught about the rear view mirror stanchion. Once the "DIM" sign has been lowered to its deployed position the driver may be hesitant to release the lanyard, for fear that, in the dark interior of the vehicle, it may not be easy to find. It would be an undesirable distraction for a driver to be groping about the upholstery for such a lanyard rather than attending to the hazards of the road. Further, the location of the hook upon the rearview mirror stanchion itself would seem to increase the likelihood that a less dextrous driver would disturb the orientation of the mirror from its chosen position. Finally, the rearwardly extending lanyard may present a snare to entangle persons entering or departing the vehicle. The depending embodiment of this sign, and of the similar depending embodiment of Sangu suggest that those seated in the rear seat had best not be of great stature, or that the sign may only be deployed when there are no passengers' heads obstructing the arc to be swept by the sign during deployment.
Finally, none of the examples of prior an describe a sign whose message is fully hidden from view when not in use. Even the folding signs of Minervini and Sangu are visible in their storage positions either to pedestrians who may view the message when the car is parked, or by persons seated within the car.
There is therefore, a need for a relatively uncomplicated movable sign for deployment within a vehicle, which neither requires an inconvenient lanyard nor a complicated microprocessor control system, which will return to its stored position without fuss, which may be activated and de-activated quickly, which will conceal its own message when not in use, which may be deployed with reduced potential for distraction of the driver, and whose deployment will not be obstructed by the heads of persons who may be seated in the rear seat.